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921.
922.
Phytochemical reinvestigation on the whole plants of Ypsilandra thibetica obtained five new spirostane glycosides, ypsilandrosides H-L (1-5), and a known saponin polyphylloside III (6). Among them, 1 and 2 are the first spirostane glycosides which possess novel 5(6 → 7) abeo-steroidal aglycones. Compounds 3 and 4 are rare saponins whose aglycones contain a hydroxyl group at C-7. Their structures were elucidated on the basis of MS, 1D and 2D NMR spectroscopic analysis and chemical evidences. The isolated compounds were evaluated for their cytotoxic activity on five tumor cell lines. 相似文献
923.
924.
Hema M Murali A Ni P Vaughan RC Fujisaki K Tsvetkova I Dragnea B Kao CC 《Molecular plant-microbe interactions : MPMI》2010,23(11):1433-1447
Brome mosaic virus (BMV) packages its genomic RNAs (RNA1, RNA2, and RNA3) and subgenomic RNA4 into three different particles. However, since the RNAs in the virions have distinct lengths and electrostatic charges, we hypothesize that subsets of the virions should have distinct properties. A glutamine to cysteine substitution at position 120 of the capsid protein (CP) was found to result in a mutant virus named QC that exhibited a dramatically altered ratio of the RNAs in virions. RNA2 was far more abundant than the other RNAs, although the ratios could be affected by the host plant species. RNAs with the QC mutation were competent for replication early in the infection, suggesting that they were either selectively packaged or degraded after packaging. In support of the latter idea, low concentrations of truncated RNA1 that co-migrated with RNA2 were found in the QC virions. Spectroscopic analysis and peptide fingerprinting experiments showed that the QC virus capsid interacted with the encapsidated RNAs differently than did the wild type. Furthermore, wild-type BMV RNA1 was found to be more susceptible to nuclease digestion relative to RNA2 as a function of the buffer pH. Other BMV capsid mutants also had altered ratios of packaged RNAs. 相似文献
925.
P-Rex1 (phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 1) is a Rac-specific guanine nucleotide exchange factor activated by Gβγ subunits and by PtdIns(3,4,5)P3. Recent studies indicate that P-Rex1 plays an important role in signaling downstream of neutrophil chemoattractant receptors. Here we report that heterologous expression of P-Rex1, but not Vav1, reconstitutes formyl peptide receptor 1 (FPR1)-mediated NADPH oxidase activation in the transgenic COSphox cells expressing gp91phox, p22phox, p67phox and p47phox. A successful reconstitution requires the expression of a full-length P-Rex1 with intact DH and PH domains, and is accompanied by P-Rex1 membrane localization as well as Rac1 activation. P-Rex1-dependent superoxide generation in the reconstituted COSphox cells was further enhanced by expression of the novel PKC isoform PKCδ and by overexpression of Akt. Heterologous expression of P-Rex1 in COSphox cells potentiated fMet-Leu-Phe-induced Akt phosphorylation, whereas expression of a constitutively active form of Akt enhanced Rac1 activation. In contrast, a dominant negative Akt mutant reduced the fMet-Leu-Phe stimulated superoxide generation as well as Rac1 activation. These results demonstrate that in COSphox cells, P-Rex1 is a critical component for FPR1-mediated signaling leading to NADPH oxidase activation, and there is a crosstalk between the P-Rex1-Rac pathway and Akt in superoxide generation. 相似文献
926.
Jun-ling Shen Xiang-nan Jia Hui-qun Ni Pei-guang Sun Shi-hui Niu Xiao-yang Chen 《Trees - Structure and Function》2010,24(3):455-462
Amplified fragment length polymorphism (AFLP) was used to determine the genetic diversity among 38 populations of Jatropha curcas L. grown in a seed source trial in Hainan Province of China. The populations studied consisted of one source from Indonesia
and 37 sources from the main cultivating areas of jatropha in China, viz. Guangdong (1), Guangxi (10), Guizhou (4), Hainan
(6), Sichuan (8) and Yunnan (8). Nine AFLP primer combinations were used to generate a total of 246 fragments, of which 72
(26.99%) were polymorphic. Three-marker attributes: polymorphism information content (PIC), marker index (MI) and resolving
power (RP), were all found to be reliable to determine the discriminatory power of the nine primer combinations. The Jaccard’s
similarity coefficient showed a high similarity range from 0.866 to 0.977, suggesting a low genetic diversity among the 38
populations. The UPGMA-based dendrogram and biplot of a principal component analysis did not reveal a clear pattern of groupings
by geographic locations of the seed sources; populations from across different provinces were mixing in the same groups. The
low genetic diversity and a lack of variation pattern among the populations in China suggest that it is necessary to import
new germplasm preferably from the species’ natural distribution range to broaden the genetic base for improvement program. 相似文献
927.
The electrochemical behaviors of the interaction of chromotrope 2R (CH2R) with human serum albumin (HSA) are investigated
on the hanging mercury drop electrode with linear sweep voltammetry. In the acidic buffer solution (pH 2.5) CH2R has a well-defined
voltammetric reductive wave at −0.34 V (SCE). On the addition of HSA into the CH2R solution, the reductive peak current of
CH2R decreases with little movement of the peak potential. The voltammetric study shows that the electrochemical parameters
of interaction solution do not change and a new electrochemically non-active complex is formed via interaction of CH2R with
HSA, which cannot be reduced on the Hg electrode and results in the decrease of the free concentration of CH2R. The decrease
of reductive peak current is proportional to HSA concentration and further used for protein detection. The binding ratio and
the binding constant are further calculated with the experimental voltammetric data. 相似文献
928.
Shun-rong Ji Chen Liu Bo Zhang Feng Yang Jin Xu Jiang Long Chen Jin De-liang Fu Quan-xing Ni Xian-jun Yu 《生物化学与生物物理学报:癌评论》2010
During the past years, great progress has been made in the field of nanomaterials given their great potential in biomedical applications. Carbon nanotubes (CNTs), due to their unique physicochemical properties, have become a popular tool in cancer diagnosis and therapy. They are considered one of the most promising nanomaterials with the capability of both detecting the cancerous cells and delivering drugs or small therapeutic molecules to these cells. Over the last several years, CNTs have been explored in almost every single cancer treatment modality, including drug delivery, lymphatic targeted chemotherapy, thermal therapy, photodynamic therapy, and gene therapy. In this review, we will show how they have been introduced into the diagnosis and treatment of cancer. Novel SWNT-based tumor-targeted drug delivery systems (DDS) will be highlighted. Furthermore, the in vitro and in vivo toxicity of CNTs reported in recent years will be summarized. 相似文献
929.